Sediment Phosphorus Release Research Articles

Measurement and verification of rates of sediment phosphorus release for a hypereutrophic urban lake

The contribution of sediment release to the phosphorus budget of hypereutrophic Onondaga Lake was determined through laboratory measurements made on intact cores. Rates ranged from 9–21 mg P m−2 d−1 with a mean of 13 mg P m−2 d−1, values similar to those observed in other lakes of comparable trophic state. There was no statistically significant trend in rates in time (July versus September) or in space (location along the major N/S axis of the lake). Rates of sediment phosphorus release measured in the laboratory compared favorably with the observed rate of soluble reactive phosphorus accumulation in the lake's hypolimnion. The sediments are the second largest source of phosphorus for Onondaga Lake, contributing 24% of the overall phosphorus load to the system.

Sorption and release of phosphorus in a peaty sediment

Sorption and release of phosphorus in a peaty sediment

Spatial Variation in the Distribution of Phosphorus Species in the Surficial Sediments of Canadohta Lake, Pennsylvania; Implications for Internal Phosphorus Loading Estimates

The concentrations of total, loosely sorbed, metal-bound, calcium-bound, and organic phosphorus, iron, and organic matter (loss on ignition) were determined for 71 surface sediment samples from Canadohta Lake, Pennsylvania. The results indicate that lake sediments can be highly variable with respect to these parameters. Most of these parameters were highly intercorrelated, and some general patterns appear to exist based on these and previously published data. Given the highly variable nature of sediment quality, particularly among these parameters which have been shown to be good predictors of sediment phosphorus release rates, estimates of internal phosphorus loading based on a few incubated cores taken from the deepest area of a lake may contain serious errors. We recommend that sediment heterogeneity be assessed in order to determine an appropriate number and distribution of cores to be incubated for internal loading estimates.

A Successful Alum/Aluminate Treatment of Lake Morey, Vermont

ABSTRACT Lake Morey, Vermont provides a case history of a successful lake restoration effort. Decades of algal blooms and a major summer fish kill preceded a hypolimnetic alum and sodium aluminate treatment in 1986. Earlier diagnostic studies with paleolimnological analyses and a detailed phosphorus budget revealed the cause to be internal phosphorus loading from anoxic hypolimnetic sediments. The aluminum treatment of these sediments resulted in sharp declines in total phosphorus and chlorophyll a concentrations, and increased Secchi transparency. The dose rate of 44 g Al/m2 appears to have been sufficient to form an effective barrier to sediment phosphorus release, and improved conditions continue to persist after four years. Elevated dissolved aluminum levels and some possible adverse effects on the benthic invertebrates and the yellow perch population were temporarily observed following the treatment. The apparent success of the project in controlling phosphorus concentrations is the result of an accu...

Internal Phosphorus Loading and Macrophytes: an Alternative Hypothesis

ABSTRACT Rooted, submersed macrophytes, primarily Elodea densa, have apparently served to restrict internal phosphorus loading during the summer in shallow Long Lake, Washington, instead of contributing phosphorus through senescence (process of aging). Internal loading was consistently controlled for five years by treatment by drawdown and alum, and mean, whole-lake macrophyte biomass ranged from about 30 to 250 g/m2 during the 12 study years. Instead of the positive relationship between macrophyte biomass and lake phosphorus content during the summer that has been observed by others, the two variables had an inverse relationship. Gross internal loading (before and after alum control), estimated by a nonsteady-state model, was greater during years when low winds (< 10 km/h) were frequently followed by high winds (> 16 km/h). This indicates the importance of stability in creating an anoxic layer over the sediment, followed by wind mixing to entrain it into the water column. Thus, rather than serving as a direct source in summer through senescence, a dense cover of macrophytes in this lake may impede sediment release of phosphorus by creating a barrier to wind mixing. Late fall and winter senescence may, however, facilitate sediment phosphorus release by the iron-redox mechanism through organic enrichment of the sediment surface. The varied role of macrophytes since treatment suggests that partial alum control may have persisted for at least nine years.

Lake restoration by reducing external phosphorus loading: the influence of sediment phosphorus release

SUMMARY. 1. This review considers the factors which determine the recovery of eutrophic lakes following a reduction in the external phosphorus loading.2 The mean phosphorus content of a lake should decrease roughly in proportion to the reduction in phosphorus input. Where the lake phosphorus concentration does not decrease as predicted, then the release of phosphorus from the sediment is implicated.3. The current understanding of the processes by which sediment phosphorus is mobilized and transported into the photic zone is described. The extent to which phosphorus release can maintain lake phosphorus concentrations following the reduction in external loading is influenced by: lake morphometry, flushing rate, sediment type, trophic state and history of enrichment.4. A reduction in the phytoplankton biomass of a lake is dependent upon the size of the decrease in lake phosphorus concentration and the degree to which phosphorus limits primary production. The importance of phosphorus in limiting phytoplankton production tends to decrease with increasing lake trophic status.5. Improvements in the condition of highly eutrophic lakes require very large reductions in external phosphorus loading, whereas in mildly enriched lakes moderate changes in the supply of phosphorus have noticeable effects on phytoplankton biomass.

Relationship between Anaerobic Sediment Phosphorus Release Rates and Sedimentary Phosphorus Species

Rates of anaerobic phosphorus release from the sediments of 57 lakes of varying trophy and sediment characteristics were measured under controlled laboratory conditions to test the hypothesis that internal phosphorus loading was a function of sediment phosphorus species. Simple regression analyses indicated that no single species can predict more than 18% of the variability in release rates. Multiple regression analysis using both water and sediment characteristics were able to explain 51% of the variation. A model based on stepwise multiple regression analysis suggests that lakes most prone to high rates of internal phosphorus loading will be alkaline with high concentrations of spring overturn total phosphorus, and with sediments characterized by high concentrations of iron-bound phosphorus, and low concentrations of organic matter.

Contribution of bacteria to release and fixation of phosphorus in lake sediments

Cycling of phosphorus at the sediment‐water interface is traditionally considered to be controlled by pH‐ and redox‐dependent, abiotic processes, such as formation and dissolution of FeOOH‐PO4 complexes. In this study, however, a large part of total P in sediments of Lake Sempach, an 87‐m deep eutrophic lake, was estimated to be incorporated in bacterial biomass. Laboratory experiments indicated that sediment microorganisms can rapidly take up and release soluble reactive P (SRP), depending on redox conditions, and that sterilization of oxic sediments decreased their SRP sorption capacity. In an in situ experiment conducted in the lake, bacteria also contributed considerably to SRP fixation when water enclosed within a sediment flux chamber was reoxygenated following anoxia. Moreover, in that experiment and in data sets from several other lakes, anoxic releases of Fe and P from sediments appeared to be partly uncoupled. As part of an ongoing revision of the classical model for P exchange across the sediment‐water interface, these results provide direct evidence that fixation and release of SRP may be controlled partly by redox‐dependent changes in microbial physiology, as well as by production and decomposition of microbial biomass.

A Pilot‐Scale Evaluation of Alum Treatments to Reduce Lake Sediment Phosphorus Release

AbstractPresented is a simple mass‐balance approach to evaluating alum inactivation of sediment‐bound phosphorus (P) using continuous‐flow reactors and aerobic sediments from a eutrophic luke (Black Lake, NY). The method permitted tests of treatment effects on the rate and duration of sediment P release, was simple to interpret, statistically reliable, and could be applied to other eutrophic systems. Analyzed as a zero‐order process, sediment P release rate decreased linearly as a function of alum dose, and the maximum dose tested (equivalent to 1.22 g Al m−2) halved the zero‐order P release rate for four hydraulic retention periods.

Contribution of bacteria to release and fixation of phosphorus in lake sediments

Contribution of bacteria to release and fixation of phosphorus in lake sediments

Hypolimnetic withdrawal in two north american lakes with anoxic phosphorus release from the sediment

Hypolimnetic withdrawal has been used to decrease eutrophication in two Connecticut lakes. This restoration technique is based on the forced discharge of nutrient-rich bottom waters in lakes with anoxic hypolimnia, while surface outflows are dammed. Internal phosphorus load amounted to 600 mg m −2 summer −1 before withdrawal. Most of this load probably originated from the sediment since the experimentally determined sediment phosphorus release rates of 2–12 mg m −2 day −1 can account for the internal load. The smaller lake responded to hypolimnetic withdrawal with decreasing epilimnetic and hypolimnetic phosphorus concentrations, decreased anoxia and internal loads. The larger lake also showed a tendency towards improvement which is, however, not statistically significant.

Suppression of phosphorus release from lake sediments by the addition of nitrate

An assessment was made of the effectiveness of nitrate in reducing phosphorus release from the anoxic sediments of a small dimictic lake, White Lough, N. Ireland. Laboratory experiments on sediment cores showed that nitrate delayed and reduced phosphorus release with an input of 61 gN m −2 causing complete suppression. The addition of 24 gN m −2 of nitrate to the sediment of White Lough resulted in a delay and reduction of phosphorus release similar to that observed in the laboratory core experiments. Sediment release of iron in the lake was also delayed and reduced but manganese release and the rate of hypolimnetic deoxygenation were unaffected by the nitrate addition. Ammonium release rates in the sediment cores and in the whole lake experiment did not vary with nitrate input. Comparing the costs of using nitrate or iron/aluminium salts to suppress sediment phosphorus release indicated that the nitrate method was at least 80% more expensive.

Loosdrecht Lakes Restoration Project: Sediment phosphorus distribution and release from the sediments

Loosdrecht Lakes Restoration Project: Sediment phosphorus distribution and release from the sediments

Lough Ennell: laboratory studies on sediment phosphorus release under varying mixing, aerobic and anaerobic conditions

SUMMARY. 1. The exchange of phosphorus between the epilimnetic (shallow zone) sediment and water column in Lough Ennell was investigated in laboratory experiments using five intact cores.2. Variations in water mixing, sediment suspension and aerobic–anaerobic oxygen status in the water column and its effects on sediment phosphorus release rates were determined.3. Experimental results indicated that phosphorus release is possible under both aerobic and anaerobic conditions. Aerobic release (0.025 mg P l−1 over 5 days) was possible up to the point when mass resuspension of sediment occurred. Anaerobic release for the same period and mixing conditions was 0.183 mg Pl−1.4. The release rate under aerobic conditions at 10°C equates to an internal areal loading of 0.134 g P m−2 yr−1, which is approximately 17% and 30% of the average total phosphorus and orthophosphate loadings respectively for the period 1974–79.5. The results clearly implicate aerobic inorganic phosphorus release from the epilimnetic sediments as a significant source of this nutrient to the overlying water column and is likely a major factor in the continuing eutrophic status in the lake.

REDUCING SEDIMENT PHOSPHORUS RELEASE RATES IN LONG LAKE THROUGH THE USE OF CALCIUM NITRATE

ABSTRACT The effect of injecting different dosage rates of calcium nitrate into the bottom sediments of Long Lake in New Brighton, Minn., was observed in a laboratory study. The purpose of the study was to determine the minimum dosage necessary to reduce phosphorus release rates from the sediments to satisfactory levels. The study included measurement of sediment phosphorus release rates under both aerobic and anaerobic conditions, and evaluated the effect of adding ferric chloride to the sediments along with the calcium nitrate. The addition of ferric chloride was included in the study to determine if the iron available in the sediment was adequate to sorb the PO4 −3when oxidized conditions were provided. The study concluded that at least for the short term (90 days), injection of calcium nitrate could eliminate virtually all phosphorus release from the sediments previously releasing phosphorus at a rate of 7 mg P/m2/day, and actually result in the sediments becoming a sink for phosphorus in the water co...

Release of sediment-phosphorus and the influence of algal growth on this process

Phosphorus release from undisturbed sediment cores was studied in a continuous flow system. Various lakes and polder ditches were compared with each other. Peaty lakes exchanged their particulate phosphorus rapidly with the overlying water as compared with other sediment types. This makes them suitable for phosphorus load reduction measures. There was found to be no simple direct relation between chemically extracted phosphorus fractions and the phosphorus released during the experiment. Algal growth in the overlying water stimulated the release of phosphorus.

Internal phosphorus loading in a shallow eutrophic lake

Internal loading of phosphorus has been implicated as a major eutrophicating factor in Long Lake, Washington (Kitsap County). As a result of such loading, summer total phosphorus concentrations approach or exceed 100 μgP l −1. Most of the summer loading of phosphorus is thought to have been released directly from the rich, flocculent sediment in the mid and northern part of the lake as a result of high pH (up to 10) related to phytoplankton photosynthesis. The lake also supports a dense submersed macrophyte crop (areal weighted mean dry weight of about 220 g m −2) composed primarily of Elodea densa. Although excretion of phosphorus from healthy E. densa was found to be minimal, the potential contribution of P indirectly from sediment via macrophyte uptake and subsequent decomposition in the winter was on the order of 200–400 kg yr −1 or about 25–50% of the external loading. Nevertheless, loading of phosphorus during predrawdown summers is thought to have originated largely as a direct release from sediment due to high pH. Estimates of sediment phosphorus release determined from laboratory experiments, mass balance and core analyses ranged from 2.2 to 5.6 mg m −2 day −1. As a component of the restoration program, the lake (mean depth of 2 m) was drawn down nearly 2 m for 4 months during the summer and fall of 1979. The lake's trophic status was expected to improve due to sediment consolidation and/or macrophyte reduction. The drawdown resulted in an 84% reduction in macrophyte biomass in 1980 but minimal sediment consolidation (0.1 m). Winter decomposition of the much smaller macrophyte crop, apparently provided insufficient phosphorus in the spring to stimulate phytoplankton and to enrich midlake sediments, which has probably occurred in previous years. Low water column pH during the postdrawndown summer of 1980 resulted from relatively low rates of plankton photosynthesis. During the summer of 1980 internal loading of phosphorus was reduced and total phosphorus remained below 50 μg l −1.

COVERING BOTTOM SEDIMENTS AS A LAKE RESTORATION TECHNIQUE1

ABSTRACT: Sediment covering to control macrophytes and sediment nutrient release is reviewed. It is concluded that fly ash application to control sediment phosphorus release presents more dangers to the lake than benefits and should not be used. Polyethylene sheeting has not had long term effectiveness due to macrophyte regrowth on its surface. PVC‐coated fiberglass screen is expensive but nontoxic and appears to give long term macrophyte control. Similar results may be obtained with spun‐bonded polypropylene. Sand, clay, and sheeting to retard nutrient release have received insufficient attention.

Changes in phytoplankton physiology and morphology in response to dissolved nutrients in Lough Neagh, N. Ireland

SUMMARY. Cell phosphorus and anthrone‐reactive carbohydrate contents were measured over a 6‐month period in the phytoplankton of Lough Neagh, N. Ireland. When all the soluble reactive phosphorus had disappeared from the water column, cell phosphorus contents began to decrease, reaching a minimum value of 0.4% ash‐free dry weight. At this time, cell carbohydrate contents greatly increased and phosphorus sorption assays showed rapid uptake of orthophosphate. Following a presumed sediment phosphorus release, cell carbohydrate and phosphorus uptake rate decreased greatly and there was a subsequent increase in cell phosphorus content to 1.6% ash‐free dry weight. As the cell phosphorus content declined, blue‐green algal filaments became progressively shorter. On the basis of these responses it is likely that phosphorus limitation occurred over a 4‐week period.

Trophic Status Related to Sediment Chemistry of Canadian Prairie Lakes

AbstractConcentrations of different sediment phosphorus forms vary in the Prairie lakes studied. Extremely high surface sediment available P concentrations in the Fishing Lakes of southern Saskatchewan were related to P loading from municipal and other cultural sources. Mean available P concentrations in surface sediments from the Fishing Lakes are higher than those found in other Prairie lakes and in most other Canadian lakes. Sediment cores show that presettlement concentrations of available P in the Fishing Lakes are higher than occur today in surface sediments from culturally eutrophied lakes, such as Lake Erie, elsewhere in Canada.Free iron is concentrated in the surface 10 to 15 cm of sediment cores from the Fishing Lakes and Lake Erie. Such a distribution, when coupled to low free Fe/available P ratios, is considered to reflect conditions favorable for P regeneration when anoxic conditions develop under winter ice cover.For the winter of 1976–1977, a mean sediment phosphorus release rate of 8.6 mg/m2 per day was calculated for the Fishing Lakes.